quiescent (adj.)
- abeyant
- abiding
- calm
- changeless
- cloistered
- constant
- contemplative
- continuing
- cool
- do-nothing
- dormant
- durable
- dwindling
- echoless
- enduring
- firm
- fixed
- frozen
- halcyon
- hushed
- idle
- immobile
- immutable
- impassive
- inactive
- inaudible
- inert
- intact
- inviolate
- isolated
- laissez-faire
- lasting
- meditative
- moldering
- motionless
- mousy
- neuter
- neutral
- noiseless
- pacific
- paralytic
- paralyzed
- passive
- peaceable
- peaceful
- permanent
- perpetual
- persistent
- placid
- potential
- quiet
- remaining
- reposeful
- restful
- resting
- rigid
- secluded
- sedentary
- sequestered
- sheltered
- silent
- smooth
- solid
- soundless
- stable
- stagnant
- standpat
- static
- stationary
- steadfast
- still
- stilly
- stoic
- stolid
- sustained
- torpid
- tranquil
- unagitated
- unaltered
- unarticulated
- unchangeable
- unchanged
- unchanging
- unchecked
- undisturbed
- unfading
- unfailing
- unhearable
- unmoved
- unperturbed
- unruffled
- unsounded
- untroubled
- unuttered
- unvaried
- unvarying
- unvoiced
- vegetative
- waning